Correlations are often used in process control system to determine the value of a physical property. Typically, the correlation is periodically updated from the results of laboratory analysis by utilizing a bias. The conventional updating procedure required calculating the result of the correlation and the current bias, recording the foregoing result, measuring the physical property by laboratory means, calculating a new bias by subtracting the laboratory measurement from the previously recorded calculated result of the correlation, and then tuning the new correlation bias. Thus, the foregoing process involves a number of steps all of which can introduce and/or increase an error in the resulting correlation bias.
Because of the foregoing, it has become desirable to develop a control logic system which eliminates the need for recording the correlation bias so that this bias can be subtracted from the measured value of the physical property being monitored and wherein the control logic can continuously update the correlation bias and is an integral part of the overall control system.